1. Field of the Invention
Aspects of the present invention relate generally to wireless communication networks and, more particularly, to a method and a device for constrained power allocation in a multiple input multiple output (MIMO) system.
2. Description of the Related Art
Communications over multiple-input-multiple-output (MIMO) channels has been the subject of intense research in recent years and has emerged as one of the most significant breakthroughs in modern communications. Communications over MIMO channels can support significantly higher data rates and greater reliability relative to communications using single-input-single-output (SISO) channels. MIMO-based communications may help to resolve the bottleneck problem limiting traffic capacity in future Internet-intensive wireless networks, for example. Many researchers also believe that MIMO-based technology is poised to penetrate large-scale, standards-driven commercial wireless products and networks such as broadband wireless access systems, wireless local area networks (WLAN), and third-generation (3G) as well as fourth-generation (4G) networks.
An essential feature of a MIMO communications system is that, by appropriately coding signals transmitted from multiple transmitting antennas to multiple receiving antennas, the system is able to turn multipath-propagation—long a problem in wireless communications—into an advantage. MIMO communications systems take advantage of random channel fading and, when possible, multipath delay spread to increase channel capacity. This is accomplished by combining at a receiver the signals transmitted from multiple transmitting antennas to multiple receiving antennas so as to increase quality in terms of the bit-error rate (BER) or the data rate (bits per second). The prospect of improvements of orders of magnitude relative to more conventional communications systems is one reason for the increased interest in MIMO-based technologies.
With respect to transceivers, most research to date has focused on linear transceiver designs. According to conventional linear transceiver designs, a channel matrix that models the characteristics of a transmission channel is diagonalized using the known technique of singular value decomposition (SVD) in order to maximize channel throughput. This conventional approach, however, can add considerable complexity to the modulation-demodulation and coding-decoding procedures needed to successfully convey signals over multiple subchannels resulting from the SVD.
Therefore, the generalized triangular decomposition (GTD) is proposed to provide the transmitters for transmitting data according to the specified constraints to improve transmission performance. However, the current GTD requires a more complicated operation and has a limited speed of computation. Using hardware directly to achieve the above method will cost a lot. Therefore, there is a need for a novel method and a device that can not only reduce the complexity and the cost, but also be rapidly implemented in the hardware.